Salt mines are special compared to other underground excavation sites: once they are closed for extraction purposes, they can be opened for visitors, or for storage purposes—all because of their unique microclimate with natural air-conditioning and constant temperature and atmospheric pressure all year.

Our collection has two main goals: to show how beautiful these artificial caves and huge underground chambers once were, and to show some of the most interesting ways these depleted salt mines are being used. Let us know in the comments if you've ever explored one.

The Praid mine was a large salt mine in central Romania, close to Praid (once Parajd, Hungary), now known for its healing effect on respiratory and allergic illnesses.

Salina Turda, the salt mine of Turda, Romania (once Torda, Hungary) has been a therapy center and tourist attraction since 1992. It's considered as one of the most beautiful underground places in the world.